Architects, planners and engineers preparing site plan drawings of developments comprising large parking areas have not heretofore had a tool adapted for use in conveniently and directly marking off parking spaces on such drawings. Site plans for developments such as office parks, shopping centers, malls, parking garages, apartments, and the like, having hundreds or thousands of parking places, can be very tedious to draw if the architect must repeatedly count off the number of increments required for a standard parking space on a conventional architect's scale. An apparatus is also needed that will permit an architect to quickly and conveniently mark off nine foot wide parking spaces on scale drawings prepared at different scales such as one inch equals 20, 30, 40, 50, 60, 100 or 200 feet.
A calculator for use in laying out angled parking stalls in parking lots has previously been disclosed in U.S. Pat. No. 4,117,313. This device, however, does not comprise scales as disclosed herein and is not similarly useful to an architect.